The Demon God of Fairy Tail
by Shadowreaper98
Summary: Cain the foster son of the dark lord Hades and the sun goddess Amaterasu and clone of Zeref joins Fairy Tail how does this change things.
1. Chapter 1

**Characters**

 **Name:** Cain

 **Race:** Demigod/Clone of Zeref

 **Magic:** Caster magic, Ice Devil slayer magic, Demon Eye magic, Amaterasu, Chain magic, Bullet magic, Grimoire law, Katsu, Spacial magic, God soul, God slayer magic, fire god slayer magic, sky god slayer magic, lightning god slayer magic, dragon slayer magic, fire dragon slayer magic, sky dragon slayer magic, lightning dragon slayer magic, poison dragon slayer magic, purgatory dragon slayer magic, shadow dragon slayer magic, Telekinesis, and telepathy.

 **Chapter 1**

 **The Son of Amaterasu and Hades**

My name is Cain I'm the foster son of the dark lord Hades and the goddess of the sun Amaterasu I was adopted by Hades after he found me and spent years training me then after I proved not to be the perfect pawn he wanted me to be he abandoned me before that though he taught me demon eye magic, amaterasu, chain magic, bullet magic, grimoire law, katsu, and spacial magic.

I wandered the world for years till I met a goddess the queen of the gods herself Amaterasu she took me in and made me a demigod by using an ancient ritual I met her daughter and my new sister Izanami Amaterasu and Izanami helped to train me in more magic they taught me God soul and I made contracts with some gods so I could borrow their power, they also taught me god slayer magic, devil slayer magic, and dragon slayer magic.

Over the years I decided that I wanted to see the world more and so I told mom I wanted to join my father's old wizard Guild Fairy tail and so I went to the mortal world and joined fairy tail, Makarov the master of the guild accepted me into the guild and I continued to train in all the magic I learned.

One day I heard about a tower being made to resurrect the dark mage Zeref Dragneel unlike most people I knew the true history of Zeref he was the way he was because of one of the gods, my mother's rival Ankhseram all Zeref wanted was to bring his brother back from the dead but Ankhseram had all those opinions of how gods shouldn't get involved with mortals and their affairs and so he cursed Zeref that if he would kill all those whom he cared about around him.

I know all this because I'm a clone of Zeref that was made as a weapon against Zeref by the magical council I asked permission from Makarov to go out and destroy the tower and free its slaves he refused to let me go so I snuck away from the Guild and made my way to the Tower of Heaven I made it there and started making my way through the tower killing any members of the cult I came across when I got to the room where they would summon Zeref's soul I saw it wasn't Zeref who are you I asked using telepathy which I had picked up from some of the mages in fairy tail.

"I am Zeref" said the dark being "no you aren't" I said "how do you know boy" said the dark mass "because I'm the weaponized clone of Zeref raised by the dark lord Hades" I said the black mass then became a girl and bowed to me "I have finally found you my lord" said the girl "what do you mean who are you" I asked "you said you are the clone of Zeref who was raised by lord Hades right" she asked "yes" I said "that makes you my lord" she said "how" I asked "I should probably tell you about myself, my name is Ultear Milkovich, I'm a member of the Grimoire heart dark mage guild and a member of its elite force the seven kin of purgatory it was a dark guild made by your father master Hades, the master said if we were to ever meet you we should swear ourselves to you and serve you" she said "ok Ultear why are you here and masquerading as Zeref" I asked "we want to find and unseal the original Zeref or make you into a new Zeref since you were made by the magic council to defeat Zeref should he ever return we thought you would also make a good replacement for him and from all the stories Lord Hades said of you I will follow you to the ends of the earth Lord Cain" she said this was alot for me to take in on one hand she worked for my father and on the other she wanted to work with me.

"Ok Ultear your first order is to spy on my father for me I will allow you to continue with this boys possesion but you must always report my father's movements to me" I said "yes lord Cain and my lord I hate to ask but could you find my mother for me I need to know if she really abandoned me" she asked "who is your mother" I asked "her name is Ur" said Ultear "I of course heard of Ur she was the best Ice mage in the eastern lands "alright Ultear i'll find your mother for you and hopefully next time we meet you will be reunited with your mother" I said "thank you my liege" said Ultear and she went back to possessing the boy and I went back to releasing all the people.

I met a scarlet haired girl and together we managed to release the other prisoners and start a revolt but by the time we finished the cult off Ultear had completely possessed the boy who I found out was named Jellal and he kicked me and the girl out of the tower "sorry my lord" I heard Ultear say in my head "it's fine Ultear" I said and I grabbed the red haired girl and teleported away to the mainland and got a train back to magnolia since I used up most of my magical energy already on the way the girl woke up and nearly freaked out I calmed her down and introduced myself and I asked for her name she told me it was Erza Scarlet I told Erza that if she wanted we could part ways or she could come with me back to fairy tail she chose to come with me back to fairy tail.

When we returned to fairy tail almost immediately the master and some others attacked me after getting a real beating and asking how stupid I could possibly be everyone calmed down and we welcomed Erza into the guild and I asked the master something "pops I'm looking for someone a woman" I said "aren't we all my boy" he said with a smirk "shut up pops, I'm looking for a woman named Ur and ice mage from the eastern lands" I said "why do you ask my boy" he said "because I met her daughter and she asked me to find her" I said "you should find her and her two students in the mountains out east" said Makarov and I set out to the east to find this Ur.

A few weeks later

A few weeks later I arrived in the village at the base of the mountain where she lived "excuse me but can you tell me where to find Ur" I asked someone "you should find her at the market with her two students Grey, and Lyon" said the person I asked "Thanks" I said and I made my way to her home when I arrived I saw her teaching two boys one with dark blue hair and one with white hair "are you Ur" I asked "yes" said Ur "can I talk to you alone" I asked "sure follow me Grey, Leon Keep training I'll be back soon" said Ur.

"So kid who are you and what do you want" Ur asked " _Ultear come to me I found your mother"_ I said telepathically to my follower and she appeared before me "mom" said Ultear looking at Ur "Ultear" said Ur and the mother and daughter embraced.

"Thank you lord Cain for finding my mother and reuniting us" said Ultear "your welcome Ultear I would help anyone find their mother as long as they don't have to live my life trying to find my mom" I said "I want to ask you and your mother and her apprentices to join the fairy tail guild we could use more strong wizards" I said "I can't leave my two students" said Ur "sorry when I said you Ur I also meant your students" I said "my liege I can't leave your fathers guild just yet give it a few more years then i'll join your guild" said Ultear "ok so Ur will you and your students come join our guild" I asked Ur went to talk it over with her students "no I will not join weaker wizards then how will I surpass you" said the white haired boy Leon and then he ran away "can your Guild make me strong enough to defeat Deliora" asked Grey "give me a minute I said and teleported away.

"I arrived where I sensed Deliora's energy and came face to face with another creation of Zeref I used my ice devil slayer magic to imprison him in a inescapable ice prison and I went back to Ultear, Ur, and Grey "he's imprisoned now" I said "how I only one spell that could trap a demon like that and if you're here you didn't use it" said Ur "I have a brand of magic specifically geared towards defeating demons called Devil slayer magic or more specifically Ice devil slayer magic this magic is geared towards defeating demons such as Deliora" I said "can you teach me to use this magic" asked Grey "I sense you have the potential to use Ice devil slayer magic but I can't teach you but I can take you to the demon who taught me" I said to him I grabbed them and went to the Ice devils realm "Ice I brought you a new vict- I mean student" I said.

After hearing my call Ice came out of his Ice cave "hello Cain who's the lucky vict- I mean student" said Ice "This is Grey Fullbuster he wants to learn the ways of Ice devil slayer magic" I said "Fullbuster, I knew a Silver Fullbuster once" said Ice "he came here to learn the ways of Ice devil slayer magic as well to kill a demon" Ice continued "my dad was here to learn this kind magic" asked Grey "yes" said Ice "how long was he here about a two years, Cain spent about two months training with me" said Ice "then I'll do it in a month" said Grey "good luck with that kid" I said grabbing Ur and teleporting away and back to fairy tail.

We arrived and I brought Ur inside and once again got attacked for taking on something bigger than me this time though it was Erza who gave me the harshest beating "never ever scare me like that again got it" said Erza and then she hugged me "i'm fine Erza where pops at" I asked "master Cain's back and he brought a another new member to the guild" shouted Erza and Ur joined the guild and everything was back to normal.

A year later

It's been a year and Grey did indeed complete his ice devil training in a month I should probably explain, time in Ice's realm moves differently than time in our realm a week here is a month there so Grey came back and joined the Guild and continued to train with Ur in Ice make magic.

I'm on my way to find Zeref's younger brother Natsu since I am Zeref's clone I have all his memories including his memories of Natsu and how he brought Natsu back to life as a demon and left him to be raised by Igneel the fire dragon king according to his memories this should be the time when he and the other dragon slayers arrive in this time period I arrived at the eclipse gate and met Layla Heartfillia a descendant of Anna Heartfillia "are you Zeref" asked Layla "no I'm his clone" I told her "I noticed the poor woman was sick and in declining health using my god soul I connected with a medicine god I knew once named Apollo and I healed her.

"What did you do to me" she asked "I healed you now we need to open the eclipse gate and bring the dragons and slayers over" I said and Layla opened the gate and out came the slayers and I could sense the dragons "hello Igneel I am the clone of Zeref that the humans made to destroy him" I said to the dragon in Natsu "hello as you must know then the plan is for me and the other dragons to heal so we can defeat a very powerful very evil dragon" said Igneel through Natsu the Dragons then retreated into their foster children's mind and I took Natsu and brought him to Fairy Tail.

 **AN: Here's a new story everyone I know it probably makes no sense right now I hope to change that as the story progresses and I know Ur and Layla being dead was a good plot point for the original story line but I want to see how these two change things for the guild so try to bare with it for now this is another Oc x harem story but also Natsu x harem story so read, like, and review see ya guys later.**


	2. Chapter 2

**Chapter 2**

I was on my way back from another S-class mission for fairy tail, after I brought Natsu to join Fairy Tail I started to help him train in different ways to use his fire and he and Gray immediately hated each other spending every moment Erza wasn't watching them arguing a few years later me, Erza, Makarov's grandson Laxus, and another mage who joined us Mystogan became S-Class wizards I received training from our strongest wizard Gildarts Clive I always thought I was the strongest mage but Clive beat me with one spell I also found out that my fellow guild mage Cana was his daughter after he left for his 100 year quest, and finally I became a member of the seven warlocks (don't own them I got the idea from another fairy tail story I read called the ruthless seven by MasterMind2553 so all credit goes to that author also I recommend the story) a group of very powerful magicians who guard over the strongest and most famous guild masters or members of the magic council.

I met a dragon named Atlas Flame who taught me his own type of fire dragon slayer magic called Purgatory dragon slayer magic, I met multiple mentors who taught me how to use all kinds of magic Makarov tells me I'm above S-class in terms of power and could probably become a SS-class mage if the rank existed I was still nowhere near Clive though, if I deserved a SS-class rank then he deserves a SSS-class rank.

Back to what I was doing I was making my way back to the guild while I was walking through I met a young woman "who are you" I asked the girl "my name is Evelyn, Evelyn Heartfillia but everyone calls me Eve" she told me "Heartfillia, are you related to Layla Heartfillia" I asked "you knew my mom wait are you Zeref Dragneel's clone that she always talked about the guy who saved her from her sickness" asked Eve "that would be me" I said.

"So where are you going" I asked "I want to join a guild my mother told me about called fairy tail, but my dad doesn't want me to be a mage he wants me to grow up and be a normal wife and businesswoman so I talked to mom and I ran away" said Eve "well as it turns out I'm a member of fairy tail and on my way there right now" really can I come with you" she asked "of course" I said and we started on our way back to the guild "so what type of magic can you use" I asked "spirit magic" she said "what's that" I asked "it allows me to have the powers, physiology, and abilities of any type of spirit" she said "that sounds alot like takeover magic" I said "it is similar to takeover magic" said Eve soon we arrived in magnolia and made our way to the guild hall magic" said Eve we made it to Magnolia and went to the guild I kicked the door in "I'm home" I said "hey everyone Cains back" said a guild member whom I didn't know "so you back god complex good you and I have unfinished business" said Laxus "bring it false slayer" I said and me and Laxus started a fight which started a fight all over and we started to freak Eve out everyone continued to fight till the master came in " **WHAT ARE YOU ALL DOING** " asked master Makarov but me and Laxus just continued to fight.

" **Lightning Dragon Raging Bolt"** screamed Laxus and fired a lightning bolt from the roof " **Lightning God's Charged Particle cannon"** screamed Cain and black and yellow lightning collided and knocked the two S-class wizards back after the two we're done the giant form of Master Makarov grabbed the two boys " **you two done** " asked Makarov "yeah I'm done pops" I said "what about you Laxus" asked Makarov "yeah I'm done gramps" said Laxus "good Cain I have a job for you" said Makarov "what is it pops" I asked "there's a meeting of the guild masters and as a member of the seven warlocks you are required to accompany me to every other meeting" said Makarov "you got it pops" I said and me and pops made our way to the train station and took it to clover.

A few hours later we arrived in Clover and I met the other guild masters as well as my fellow warlocks I made friends with a few except one his name was Abel and like me he was a god slayer a metal god slayer and foster son of Vulcan the Roman god metal and I hated him more than I hated Laxus and trust me that's a lot of hate it probably was the influence of our master Makarov and Jose Porla hating each other.

The meeting went on for a few days the masters discussing things and I found that the phantom lord master and his warlock we're incredibly arrogant and me and Master Makarov made our way home and that was the first and last time I ever met the prince of Phantom Lord and we went home and I got back to work.

 **AN: I know it's short but I can't think of what else to do with this chapter and Eve is Lucy's older sister and the Phantom Lord saga will be about both of them any way review and I'll try to have this story updated as soon as I can, I don't know who made the first fairy tail story about seven warlocks but I read part of one and I enjoyed it and thought it was a good story so whoever made up the seven warlocks I hope you don't mind me using the name.**


	3. Chapter 3

**Chapter 3**

Me and Eve were making our way back to the guild after another S-class quest we were passing through Haregaon a fishing village close to Magnolia while we were there we there we heard a commotion near the beach and we saw a mermaid, a blonde girl, and a very familiar blue cat with a green pack on its back "Cain isn't that Happy down there" asked Eve "yeah think its is which means Natsu must be here somewhere" I said "wait I know that girl and mermaid" said Eve "since when do you know mermaids" I asked "that mermaid is Aquarius she's one of my mom's celestial spirits and that blonde girl is my younger sister Lucy" said Eve.

Aquarius attacked a ship and sent it to the beach "I better go check on my sister and Happy" Eve went down to check on the three so I decided to go see if Natsu was ok on the ship.

Eve

I made my way down to the beach "Lucy, Happy are you two ok" I asked the cat and my sister "Evelyn what are you doing here" asked Happy "me and Cain were on our way back to the guild and we met up with you "hey Lucy it's nice to see you again baby sis" I said "Evelyn is that really you" Lucy asked me "yeah, Aquarius why are you not behaving for Lucy" I asked "because I don't like her" said Aquarius "get over it fish girl" I said we then saw a black and normal flame.

"Bora I think I know who these two are there the real Salamander and Erebus Cain" said one of pirates "wait did he say Erebus Cain as in the Erebus Cain" said Lucy "yep little sis, Erebus Cain the wizard who can use the dark flames, winds, and lightning of god's" I said "kid let me show you true power" said Cain " **Lightning Fire God's explosive flaming 120mm lightning cannon** " said Cain and a black flame surrounded in electricity shot at the feet of the pirates and there was a smoking crater.

"See kid, that's true fire power" said Cain "you're awesome Cain" said Natsu "now Natsu show this guy true fire power" said Cain and Natsu and the false Salamander continued their fight and Natsu won.

"Well Eve let's head home" and the duo made their way back to magnolia.

Cain and Eve got on a train to Magnolia and made their way home the duo arrived back at Fairy Tail at the same time as Natsu, Lucy, and Happy the five went inside and almost immediately a fight started even Eve got involved in the fight which surprised Lucy considering last time she saw her sister she hated to fight to much, eventually Makarov arrived and broke up the fight and lectured his children and Natsu took the job to find Makao "hey Eve, Mira I was wondering why are Natsu and Cain so close"asked Lucy "well Cain is the one who brought Natsu here when he was young, and probably cause Cain has always acted like an older brother to Natsu ever since they were kids, Cain even brought Natsu to live with him and essentially took care of him Natsu really needed it especially after losing Igneel" said Mirajane "plus didn't Cain and Erza teach Natsu all the things that Igneel didn't" asked Eve "yep" said Mira "I think I'll join Natsu" said Lucy and she left.

Lucy and Natsu went to mount huckabay and saved Macao after a few days of just hanging around the guid Cain and Makarov had to leave for a conference with the other guild masters and warlocks.

 **AN: Another short chapter next chapter is the Eisenwald arc mostly because I don't know how to get into it in this chapter so like and review please.**


	4. Chapter 4

**Chapter 4**

Me and Makarov were at the meeting in Clover talking to the other masters and warlocks "I have to say Cain I never expected to see your guild rise so far in the ranks, and I have to say those boys of yours Natsu and Gray are quite tasty but not as tasty as their big brother" said a green haired mage with the symbol of blue pegasus this is Karen Lilica the warlock of blue pegasus and yes she is flirting with Cain.

"Really Karen" said Cain "i've heard Fairy tail is getting into some trouble with magic council as of late, I heard they nearly blew up a town" said a wild looking wizard this was Guy Aleus a Warlock of the Quatro Cerberus guild "let them worry they're just jealous my fellow Fairy Tail wizards are hot" said Cain "oh my you're so naughty Cain I can think of so many ways we can use that naughty personality, by the way I heard you got yourself a new recruit I heard it was Evelyn's younger sister" said Karen still flirting up a storm with Cain "oh you mean Lucy yes she's quite the blond firecracker just like her sister oh and Karen maybe later" said Cain just a flirtatiously to the green haired girl who now had a lustful smile on her face.

"Cain come here" said master Makarov "yes master" said Cain I need you to start heading for Oshibana" said Makarov "why" asked Cain "because Erza, Natsu, and Gray have teamed up" said Makarov "WHAT without me there they could definitely destroy a town" said Cain "I'll leave right away master" said Cain and he headed outside and using his Sky magic he took to the air and flew to the next town over but he didn't go far before he saw Natsu and Happy and he landed and say Natsu get knocked off the tracks "no NATSU" screamed Cain he looked up and saw Erigor the reaper "well if it isn't Erebus Cain the god slayer and prince of fairy tail care to test your power against a real wizard Erebus" asked Erigor "you know Erigor I've met the actual grim reaper and let me tell you this she doesn't like people like you using her name" said Cain.

Erigor shot his wind magic at Cain but he easily dodged it "fire god's explosive flame" shouted Cain and he punched a pure black flame towards Erigor "wind scythe" shouted Erigor and he shot sharp blades of wind at the god slayer "Lightning god's 120mm proton cannon" shouted Cain as he shot lightning at the self proclaimed reaper.

The lightning struck Erigor and knocked him down finally Natsu came flying out of the ravine "Natsu there you are what do you say we finish this guy off " said Cain "I agree Cain" said Natsu "Fire dragon's roar" said Natsu shooting flames from his mouth "fire gods below" said Cain shooting a black flame from his mouth both flames knocked Erigor out and a magic mobile drove up and Erza, Gray, Evelyn, and Lucy got out.

"Titania, Gray, Evelyn, Lucy glad you guys could join us." said Cain "hello Erebus when did you get here?" said Erza "Just now Titania." said Cain "Hey Evelyn why are they calling themselves by their nicknames?" asked Lucy "as you know Cain is called Erebus the demon god of Fairy Tail and Erza is called Titania queen of the fairies it's a way that they show each other respect." said Evelyn.

"Ok Erza what was so important that you needed to risk destroying a city by teaming up with Natsu and Grey" asked Cain and Erza explained everything to Cain "So Eisenwald got ahold of lullaby?" asked Cain "yes." said Erza "ok where did it go?" asked Cain "what?" asked Natsu "the demon flute." said Cain then the magic mobile started moving and a shadowy arm had lullaby.

The Fairy Tail wizards chased after the shadow wizard but because he was in the magic mobile they couldn't catch him in time Cain knew that he had to stop Lullaby it wasn't just a death magic flute it was a literal demon that Zeref gave life to, an Etherius.

They arrived at the building where the meeting was taking place and they found Kage Cain had finally gotten his name they saw him talking to Makarov about to play lullaby but Makarov gave a speech and they saw him throw lullaby on the ground and surrender to Makarov the fairy tale wizards came out of the bushes.

They were congratulating their master till Lullaby came to life and turned into a giant wood demon.

"Well this just got fun." said Cain "Erza, Natsu, Grey lets go." said Cain Erza changed into her heaven's wheel armor, and Cain summoned his fire scythe " _Fire God's Scythe._ " said Cain now holding a black flaming scythe and started attacking the demon, " _Ice Make: Lance._ " said Grey, " _Fire Dragon Iron Fist._ " said Natsu and the fairy tail wizards attacked the demon full force Natsu punching the demon Cain slicing at the demon with his Scythe, Erza slicing the demon with dual sword, and Grey attacking with his Ice lance.

The Fairy Tail wizards continued to press the attack unleashing even more powerful attacks Erza even changing into a more demonic armor, till Cain unleashed one of his most powerful fire god slayer spells "hey Lullaby daddies here." said Cain " _When you burn down the west… and you burn down the east…_ _ **Fire God's Kagutsuchi!**_ " saud Cain forcing the demon back into its flute form.

They then noticed that they destroyed the conference hall and probably a few mountains to Cain picked up Lullaby and put it in a glass box and put a seal on it he then noticed that they were being chased by the other wizards "well shit." said Cain and he and the group ran.

 **AN: Ok for anyone who forgot Cain is Zeref's clone so he has all his memories that includes memories of the Etherious so when he said to lullaby daddy's here it was quite literal and mocking since Zeref is technically the father of the Etherious, and yes Cain is completely aware of Natsu's Etherious nature.**


End file.
